US4069240A - Nuclear hydrogenation of n-aryl carbamates - Google Patents

Nuclear hydrogenation of n-aryl carbamates Download PDF

Info

Publication number
US4069240A
US4069240A US05/610,359 US61035975A US4069240A US 4069240 A US4069240 A US 4069240A US 61035975 A US61035975 A US 61035975A US 4069240 A US4069240 A US 4069240A
Authority
US
United States
Prior art keywords
catalyst
carbamate
dimethyl
acid
methyl
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US05/610,359
Inventor
Russell E. Malz, Jr.
Harold Greenfield
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Uniroyal Chemical Co Inc
Original Assignee
Uniroyal Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Uniroyal Inc filed Critical Uniroyal Inc
Priority to US05/610,359 priority Critical patent/US4069240A/en
Priority to CA259,244A priority patent/CA1075259A/en
Priority to DE19762639842 priority patent/DE2639842A1/en
Priority to IT69159/76A priority patent/IT1070301B/en
Priority to GB36565/76A priority patent/GB1551832A/en
Priority to FR7626711A priority patent/FR2322859A1/en
Priority to JP51105077A priority patent/JPS5233653A/en
Application granted granted Critical
Publication of US4069240A publication Critical patent/US4069240A/en
Assigned to UNIROYAL CHEMICAL COMPANY, INC., WORLD HEADQUARTERS, MIDDLEBURY, CT. 06749, A CORP. OF NEW JERSEY reassignment UNIROYAL CHEMICAL COMPANY, INC., WORLD HEADQUARTERS, MIDDLEBURY, CT. 06749, A CORP. OF NEW JERSEY ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNIROYAL, INC., A NEW YORK CORP.
Assigned to UNIROYAL CHEMICAL COMPANY, INC. reassignment UNIROYAL CHEMICAL COMPANY, INC. ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: UNIROYAL, INC., A NJ CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D207/00—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom
    • C07D207/02—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom
    • C07D207/04—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having no double bonds between ring members or between ring members and non-ring members
    • C07D207/10—Heterocyclic compounds containing five-membered rings not condensed with other rings, with one nitrogen atom as the only ring hetero atom with only hydrogen or carbon atoms directly attached to the ring nitrogen atom having no double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D207/16—Carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals

Definitions

  • This invention relates to a method for the nuclear hydrogenation of N-aryl carbamates to N-alicyclic carbamates using rhodium, ruthenium, palladium, nickel, and cobalt catalysts, and to the use of an acid promoter to enhance the utility of the rhodium and the palladium catalysts and to permit the use of a platinum catalyst.
  • the nuclear hydrogenation of N-aryl carbamates to N-alicyclic carbamates in accordance with this invention is the key step in the most efficient route for the conversion of readily available, low cost aromatic isocyanates to non-discoloring, N-alicyclic polyurethanes.
  • the aromatic diisocyanates are first converted to N-aryl dicarbamates by simply reacting with an alcohol, preferably methanol.
  • the resulting N-aryl carbamate is then converted to the corresponding N-alicyclic carbamate by the method of this invention.
  • the N-alicyclic carbamate can then be converted to valuable non-discoloring polyurethanes by transesterification reactions (transcarbamation) with an appropriate diol or mixture of diols.
  • the conventional method for such polyurethane manufacture uses N-alicyclic isocyanates prepared from the corresponding N-alicyclic diamines by phosgenation reactions.
  • the alicyclic dicarbamates are more efficiently and more economically prepared than the corresponding alicyclic diisocyanates, and also have the great advantage of being easily handled, chemically stable, and non-toxic.
  • N-aryl carbamate Any N-aryl carbamate may be employed in the invention, including, for example, those of the following formulas I and II: ##STR1##
  • n is an integer having a value from 1 to 3, preferably 2:
  • R is a moiety such as an alkyl group of from 1 to 18 carbon atoms, preferably 1 to 4 carbon atoms, a cycloalkyl group of from 5 to 8 carbon atoms, preferably 5 to 6 carbon atoms (such as cyclohexyl), an aryl group of from 6 to 12 carbon atoms (such as phenyl), an aralkyl or alkaryl group of from 7 to 12 carbon atoms (such as tolyl, xylyl, ethylphenyl, benzyl, phenethyl), or the like, alkyl being preferred (such as methyl, ethyl, propyl, isopropyl, n-, sec-, iso- and tert-butyl);
  • R 1 is hydrogen (preferred), an alkyl group of from 1 to 8 carbon atoms (such as methyl, ethyl, prop
  • a and b are integers having values of 1 to 2, the sum of (a) plus (b) being a whole value of from 2 to 4, preferably 2 to 3;
  • R 2 and R 6 may be the same or different and may have the meanings stated for R in formula I above;
  • R 3 and R 5 may be the same or different and may have the meanings stated for R 1 in formula I above;
  • R 4 may be a single bond, --O--, C 1 - C 8 alkylene (such as methylene, ethylene, tetramethylene and hexamethylene), C 5 - C 8 cycloalkylene (such as cyclohexylene), C 2 - C 8 alkylidene (such as ethylidene and isopropylidene), or C 2 - C 8 alkenylene (such as vinylene).
  • Ar 1 and Ar 2 may be the same or different and are di- or trivalent groups derived from radicals having the meanings assigned to Ar in formula I, especially phen
  • aromatic carbamates useful in the invention include methyl carbanilate, isopropyl carbanilate, stearyl carbanilate, benzyl carbanilate, phenyl carbanilate, methyl 2-methylcarbanilate, methyl 3-methylcarbanilate, methyl 4-methylcarbanilate, ethyl 4-methylcarbanilate, propyl 4-methylcarbanilate, isopropyl 4-methylcarbanilate, methyl 2-ethylcarbanilate, methyl 2,3-diethylcarbanilate, methyl 2,4-diethylcarbanilate, methyl 2,5-diethylcarbanilate, methyl 2,6-diethylcarbanilate, methyl 3,4-diethylcarbanilate, methyl 3,5-diethylcarbanilate, methyl 2,4,6-trimethylcarbanilate, methyl 4-propylcarbanilate, ethyl 4-butylcarbanilate, methyl 2-biphenylcarbamate
  • the catalysts employed for the nuclear hydrogenation of N-aryl carbamates in accordance with the invention are the group VIII transition metals, particularly rhodium, ruthenium, palladium, platinum, nickel and cobalt, preferably rhodium and ruthenium, and most preferably rhodium.
  • group VIII transition metals particularly rhodium, ruthenium, palladium, platinum, nickel and cobalt, preferably rhodium and ruthenium, and most preferably rhodium.
  • the unpredictable nature of the effect of acid is illustrated by the fact that it promotes the activity of rhodium and palladium catalysts, dramatically increases the activity of the platinum catalyst which is ordinarily inoperative in the described hydrogenation process, but actually decreases the activity of the ruthenium catalyst.
  • the acid treatment is most suitably accomplished in situ by adding a small amount of acid directly to the reaction mixture.
  • the acid treatment is most conveniently effected by washing the recovered catalyst with acid prior to reuse of the catalyst.
  • the acid may be an inorganic acid, such as sulfuric, hydrochloric, phosphoric and nitric acids, or an organic acid, such as acetic, propionic, butyric, succinic and maleic acids.
  • the acid may be added per se or as an appropriate solution of dilute acid, the inorganic acids being particularly suitable for this purpose.
  • concentrated acids or dilute solutions of acid also are appropriate.
  • the catalysts may be prepared and used either unsupported or supported on a suitable carrier such as carbon, alumina, silica, silica-alumina, alkaline earth carbonates, kieselguhr, zeolites, pumice, clay, cellulose, asbestos, etc. They may be prepared and used as powders for slurry reactions or as pellets, spheres, or granules for fixed bed reactions.
  • a suitable carrier such as carbon, alumina, silica, silica-alumina, alkaline earth carbonates, kieselguhr, zeolites, pumice, clay, cellulose, asbestos, etc.
  • the hydrogenation process may be carried out in the absence of any solvent medium, or preferably in the presence of an inert organic solvent, including, for example, aliphatic or cycloaliphatic alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, tert-amyl alcohol, n-hexyl alcohol, cyclohexanol, n-octyl alcohol, 2-ethylhexanol, n-decyl alcohol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, ethylene glycol, propylene glycol, glycerol etc.; ethers, such as diethyl ether
  • the hydrogenation may be run at temperatures ranging from room temperature or below, for example, 5°, to over 200°, for example 250°, preferably 25°-200° C., or other temperatures as high as the stability of the reactants and products will permit, and at pressures ranging from atmospheric pressure or below to pressures as high as economically practical, for example, up to 10,000 psi.
  • Preferred is a somewhat elevated pressure of, for example, 10 psi, up to, for instance, 5000 psi, usually 100 to 2500 psi.
  • Reaction times may vary widely, ranging from a few seconds to 24 hours or longer, usually 0.1 - 15 hours.
  • the conditions may be varied to provide an optimum economic combination of temperature, pressure, catalyst level, and cycle time for any given starting material and catalyst.
  • the hydrogenation reaction may be carried out in either batch or continuous systems, with either tank or pipe-line or tubular reactors, operation in a manner well known to those skilled in the art.
  • Table I illustrate the use of several catalysts for the nuclear hydrogenation of methyl carbanilate to methyl cyclohexylcarbamate. Rhodium is considerably more active than the other catalysts, and platinum shows no apparent activity.
  • a mixture of 20.1 g. (0.10 mole) of methyl 1-naphthylcarbamate, 100 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave.
  • the vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig.
  • the autoclave was agitated at 22°-31° and 500-800 psig for 3.7 hr., followed by an additional 0.8 hr. with little or no gas absorption.
  • the autoclave was cooled and depressurized.
  • the reaction product was removed and filtered through Celite filter aid to remove the catalyst.
  • the solvent was removed in a rotary evaporator under vacuum.
  • Table III illustrates how the purity of the N-aryl carbamate, in this case 4,4'-methylenedicarbanilate, greatly effects its rate of rhodium-catalyzed hydrogenation. Attempted hydrogenations of dimethyl 4,4'-methylenedicarbanilate that had been prepared under non-anhydrous conditions always resulted in catalyst poisoning and poor conversions.
  • Table IV illustrates the interrelated effects of catalyst level and temperature on reaction rate and catalyst inhibition in the rhodium-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate.
  • catalyst poisoning produces a decrease in conversion in going from 75° to 100°, and, in spite of a very rapid initial rate of hydrogenation, even more severe poisoning and lower conversion at 150°.
  • the catalyst poisoning is less pronounced because of the larger number of active sites, and the hydrogenation rate increases with increasing temperature in the lower range of 50° to 100°.
  • the obvious explanation is that higher temperatures result in greater rates of nuclear hydrogenation, but also produce increasing quantities of by-products that poison the catalyst.
  • the severity of poisoning will be inversely related to the amount of catalyst present.
  • a mixture of 20.0 g. (0.064 mole) of dimethyl 4,4'-methylenedicarbanilate (batch II), 100 ml. of 2-propanol, and 0.8 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave.
  • the vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig.
  • the autoclave was agitated at 75° and 500-800 psig for 3.0 hr., followed by an additional 0.8 hr. with little or no gas absorption. The gas absorption was aproximately quantitative.
  • the autoclave was cooled and depressurized.
  • the reaction product was removed and the catalyst separated from the reaction mixture by centrifugation, and then washed successively with three 600-ml. portions of methanol, one 300-ml. portion of 2-propanol, and one 150-ml. portion of 2-propanol.
  • the solvent was removed from the reaction product in a rotary evaporator under vacuum.
  • the white solid residue was dried in a vacuum dessicator and consisted of 20.4 g. (98% yield) of a mixture of isomers of dimethyl 4,4'-methylenedicyclohexylcarbamate, m.p. 128°-135°.
  • Anal. Calcd. for C 17 H 30 N 2 O 4 C, 62.56; H, 9.25; N, 8.58. Found: C, 63.10; H, 9.26; N, 8.35.
  • Table VI illustrates how the rhodium catalyst recovered from the hydrogenation of dimethyl 4,4'-methylenedicarbanilate retains sufficient activity to permit several reuses. Furthermore, examples 48 and 49 illustrate how extremely efficient an acid wash is in restoring the activity of the used catalyst. Part of the enhanced activity in these experiments may be the result of acid promotion (see Tables II and V) by traces of acid remaining on the catalyst from the acid wash.
  • Table VII shows the feasibility of catalyst reuse in the rhodium-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate with acid promotion, both with and without an acid wash of the recovered catalyst.
  • a mixture of 23.6 g. (0.064 mole) of diisopropyl 4,4'-methylenedicarbanilate, 97 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave.
  • the vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig.
  • the autoclave was agitated at 40° and 500-800 psig for 7.6 hr., followed by an additional 1.1 hr. with little or no gas absorption.
  • the autoclave was cooled and depressurized.
  • the reaction product was removed and filtered through Celite filter aid to remove the catalyst.
  • Example 52 was repeated at 75° for 6.0 hr. Approximately the theoretical gas absorption took place in 3.0 hr., with most of the reaction completed below reaction temperature, followed by a slow gas absorption for 3.0 hr. at 75° and little or no absorption in the last 3.0 hr. at 75°.
  • Magne Drive autoclave The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 425-800 psig. for 7 hr. at 50° followed by 13 hr.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
  • Catalysts (AREA)
  • Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)

Abstract

N-Alicyclic carbamates, useful in making polyurethanes, are prepared by nuclear hydrogenation of an N-aryl carbamate using a group VIII transition metal catalyst. E.g., dimethyl 4,4'-methylenedicarbanilate is contacted with hydrogen and ruthenium catalyst in 2-propanol medium, at 50° C. for 1.3 hours under a pressure of 500-800 psi, to form dimethyl 4,4'-methylenedicyclohexylcarbamate. Acid activation of catalyst is a feature of the invention.

Description

This invention relates to a method for the nuclear hydrogenation of N-aryl carbamates to N-alicyclic carbamates using rhodium, ruthenium, palladium, nickel, and cobalt catalysts, and to the use of an acid promoter to enhance the utility of the rhodium and the palladium catalysts and to permit the use of a platinum catalyst.
The nuclear hydrogenation of N-aryl carbamates to N-alicyclic carbamates in accordance with this invention is the key step in the most efficient route for the conversion of readily available, low cost aromatic isocyanates to non-discoloring, N-alicyclic polyurethanes. The aromatic diisocyanates are first converted to N-aryl dicarbamates by simply reacting with an alcohol, preferably methanol. The resulting N-aryl carbamate is then converted to the corresponding N-alicyclic carbamate by the method of this invention. The N-alicyclic carbamate can then be converted to valuable non-discoloring polyurethanes by transesterification reactions (transcarbamation) with an appropriate diol or mixture of diols. The conventional method for such polyurethane manufacture uses N-alicyclic isocyanates prepared from the corresponding N-alicyclic diamines by phosgenation reactions. The alicyclic dicarbamates are more efficiently and more economically prepared than the corresponding alicyclic diisocyanates, and also have the great advantage of being easily handled, chemically stable, and non-toxic.
Any N-aryl carbamate may be employed in the invention, including, for example, those of the following formulas I and II: ##STR1##
In formula I, n is an integer having a value from 1 to 3, preferably 2: R is a moiety such as an alkyl group of from 1 to 18 carbon atoms, preferably 1 to 4 carbon atoms, a cycloalkyl group of from 5 to 8 carbon atoms, preferably 5 to 6 carbon atoms (such as cyclohexyl), an aryl group of from 6 to 12 carbon atoms (such as phenyl), an aralkyl or alkaryl group of from 7 to 12 carbon atoms (such as tolyl, xylyl, ethylphenyl, benzyl, phenethyl), or the like, alkyl being preferred (such as methyl, ethyl, propyl, isopropyl, n-, sec-, iso- and tert-butyl); R1 is hydrogen (preferred), an alkyl group of from 1 to 8 carbon atoms (such as methyl, ethyl, propyl, isopropyl, n-, sec-, and tert-butyl), a cycloalkyl group of from 5 to 8 carbon atoms (such as cyclohexyl), or an aryl group of from 6 to 12 carbon atoms (such as phenyl); Ar is an aromatic group having a valence of n and having from 6 to 18 carbon atoms, containing up to 4 fused rings, and may if desired include various substitutents such as alkyl C1 - C18, cycloalkyl C5 - C8, aryl C6 - C10 (e.g., phenyl, naphthyl), alkaryl or aralkyl C7 - C15, alkoxy C1 - C18, cycloalkoxy C5 - C8, phenoxy, benzoxy, alkanoyl C2 - C13, carbalkoxy C2 - C14, or similar substituents. Ar is frequently of phenyl, tolyl or naphthyl origin.
In formula II, a and b are integers having values of 1 to 2, the sum of (a) plus (b) being a whole value of from 2 to 4, preferably 2 to 3; R2 and R6 may be the same or different and may have the meanings stated for R in formula I above; R3 and R5 may be the same or different and may have the meanings stated for R1 in formula I above; R4 may be a single bond, --O--, C1 - C8 alkylene (such as methylene, ethylene, tetramethylene and hexamethylene), C5 - C8 cycloalkylene (such as cyclohexylene), C2 - C8 alkylidene (such as ethylidene and isopropylidene), or C2 - C8 alkenylene (such as vinylene). Ar1 and Ar2 may be the same or different and are di- or trivalent groups derived from radicals having the meanings assigned to Ar in formula I, especially phenylene, tolylene, xylylene and biphenylene.
Examples of aromatic carbamates useful in the invention include methyl carbanilate, isopropyl carbanilate, stearyl carbanilate, benzyl carbanilate, phenyl carbanilate, methyl 2-methylcarbanilate, methyl 3-methylcarbanilate, methyl 4-methylcarbanilate, ethyl 4-methylcarbanilate, propyl 4-methylcarbanilate, isopropyl 4-methylcarbanilate, methyl 2-ethylcarbanilate, methyl 2,3-diethylcarbanilate, methyl 2,4-diethylcarbanilate, methyl 2,5-diethylcarbanilate, methyl 2,6-diethylcarbanilate, methyl 3,4-diethylcarbanilate, methyl 3,5-diethylcarbanilate, methyl 2,4,6-trimethylcarbanilate, methyl 4-propylcarbanilate, ethyl 4-butylcarbanilate, methyl 2-biphenylcarbamate, methyl 4-biphenylcarbamate, methyl 5-indanylcarbamate, methyl 1-naphthylcarbamate, methyl 2-naphthylcarbamate, methyl 5-acenaphthenylcarbamate, ethyl 1-anthracenecarbamate, isopropyl 2-anthracenecarbamate, methyl 6-chrysenecarbamate, methyl 2-cymenecarbamate, ethyl 3-fluoranthenecarbamate, methyl 2-fluorenylcarbamate, methyl 9-phenanthrenecarbamate, isopropyl 1-pyrenecarbamate, methyl 3-methoxycarbanilate, ethyl 2-ethoxycarbanilate, methyl 4-ethoxycarbanilate, methyl 4-propoxycarbanilate, methyl 4-phenoxycarbanilate, methyl 2-methoxy-5-methylcarbanilate, methyl 4-methoxy-2-methylcarbanilate, methyl 2,4-dimethoxycarbanilate, methyl 2,5-dimethoxycarbanilate, methyl 3,5-dimethoxycarbanilate, methyl 3,4-diethoxycarbanilate, methyl 3,4,5-trimethoxycarbanilate, butyl 2,4,5-trimethoxycarbanilate, methyl 2-carbomethoxycarbanilate, methyl 3-carbomethoxycarbanilate, methyl 4-carbomethoxycarbanilate, ethyl 3-carboethoxycarbanilate, ethyl 4-carboethoxycarbanilate, methyl 4-carbophenoxycarbanilate, methyl 2-acetylcarbanilate, methyl 3-acetylcarbanilate, ethyl 4-acetylcarbanilate, methyl 1-(9-oxofluorenyl)carbamate, methyl 2-(9-oxofluorenyl)carbamate, dimethyl 1,2 -benzenedicarbamate, dimethyl 1,3-benzenedicarbamate, dimethyl 1,4-benzenedicarbamate, dimethyl 2,4-toluenedicarbamate, diethyl 2,4-toluenedicarbamate, diisopropyl 2,4-toluenedicarbamate, dimethyl 2,5-toluenedicarbamate, dimethyl 2,6-toluenedicarbamate, dimethyl 3,4-toluenedicarbamate, dimethyl 4,4'-methylenedicarbanilate, diethyl 4,4'-methylenedicarbanilate, dipropyl 4,4'-methylenedicarbanilate, diisopropyl 4,4'-methylenedicarbanilate, dibutyl 4,4'-methylenedicarbanilate, distearyl 4,4'-methylenedicarbanilate, dimethyl 2,2'-biphenyldicarbamate, dimethyl 2,4'-biphenyldicarbamate, dimethyl 3,3'-biphenyldicarbamate, dimethyl 4,4'-biphenyldicarbamate, 4,4'-oxybis(methyl carbanilate), dimethyl 4,4'-diphenylethylenedicarbamate, dimethyl 4,4'-(N-methyldiphenylamine)dicarbamate, dimethyl 4,4'-(3,3'-dimethylbiphenyl)dicarbamate, dimethyl 1,2-naphthalenedicarbamate, dimethyl 1,5-naphthalenedicarbamate, diisopropyl 1,5-naphthalenedicarbamate, dimethyl 1,8-naphthalenedicarbamate, dimethyl 2,3-naphthalenedicarbamate, dimethyl 9,10-phenanthrenedicarbamate, dimethyl 4,5-acenaphthenedicarbamate, dimethyl 2,3-fluorenedicarbamate, dimethyl 2,5-fluorenedicarbamate, dimethyl 2,7-fluorenedicarbamate, dimethyl 4,5-dimethyl-1,2-benzenedicarbamate, dimethyl 4-methoxy-1,2-benzenedicarbamate, dimethyl 4-methoxy-1,3-benzenedicarbamate, dimethyl 3,3'-dimethoxy-4,4'-biphenylcarbamate, dimethyl 2,3-(9-fluorenone)dicarbamate, trimethyl 1,3,5-benzenetricarbamate, trimethyl 1,2,4-benzenetricarbamate, trimethyl 2,4,6-toluenetricarbamate, trimethyl 2,3,4-toluenetricarbamate, trimethyl 2,4,5-toluenetricarbamate, trimethyl 1,3-dimethyl-2,4,6-benzenetricarbamate, triethyl 1-ethoxy-2,4,6-benzenetricarbamate, triethyl 1-methoxy-2,4,6-benzenetricarbamate, dibutyl 1-carbophenoxy-3,5-benzenedicarbamate, diethyl 1-carbomethoxy-3,5-benzenedicarbamate, diethyl 1-carboethoxy-2,3-benzenedicarbamate, dimethyl 2,2'-benzophenonedicarbamate, dimethyl 3,3'-benzophenonedicarbamate, dimethyl 4,4'-benzophenonedicarbamate, methyl N-methylcarbanilate, ethyl N-methylcarbanilate, methyl N-ethylcarbanilate, dimethyl 4,4'-methylenedi(N-methylcarbanilate), diethyl 4,4'-methylenedi(N-methylcarbanilate), dimethyl 4,4'-methylenedi(N-ethylcarbanilate), dimethyl N,N'-dimethyl-2,4-toluenedicarbamate, dimethyl N,N'-diethyl-2,6-toluenedicarbamate, 4,4'-oxybis(methyl N-methylcarbanilate), 4,4'-oxybis (ethyl N-methylcarbanilate), 4,4'-oxybis(ethyl N-ethylcarbanilate), etc.
The catalysts employed for the nuclear hydrogenation of N-aryl carbamates in accordance with the invention are the group VIII transition metals, particularly rhodium, ruthenium, palladium, platinum, nickel and cobalt, preferably rhodium and ruthenium, and most preferably rhodium. In accordance with a preferred practice of the invention, it has been found that treatment of rhodium catalyst with an acid causes increased activity and permits extensive reuse of the catalyst, with a resulting important decrease in cost. Thus, the activity of a rhodium catalyst is markedly promoted by the addition of acid. Furthermore, repeated catalyst reuse is feasible when the spent catalyst is treated with acid. The unpredictable nature of the effect of acid is illustrated by the fact that it promotes the activity of rhodium and palladium catalysts, dramatically increases the activity of the platinum catalyst which is ordinarily inoperative in the described hydrogenation process, but actually decreases the activity of the ruthenium catalyst. In the case of a fresh catalyst, the acid treatment is most suitably accomplished in situ by adding a small amount of acid directly to the reaction mixture. For the purpose of reactivating used catalyst, the acid treatment is most conveniently effected by washing the recovered catalyst with acid prior to reuse of the catalyst. The acid may be an inorganic acid, such as sulfuric, hydrochloric, phosphoric and nitric acids, or an organic acid, such as acetic, propionic, butyric, succinic and maleic acids. For the in situ treatment of fresh catalysts, the acid may be added per se or as an appropriate solution of dilute acid, the inorganic acids being particularly suitable for this purpose. For the washing treatment of recycled catalyst, concentrated acids or dilute solutions of acid also are appropriate.
The catalysts may be prepared and used either unsupported or supported on a suitable carrier such as carbon, alumina, silica, silica-alumina, alkaline earth carbonates, kieselguhr, zeolites, pumice, clay, cellulose, asbestos, etc. They may be prepared and used as powders for slurry reactions or as pellets, spheres, or granules for fixed bed reactions.
The hydrogenation process may be carried out in the absence of any solvent medium, or preferably in the presence of an inert organic solvent, including, for example, aliphatic or cycloaliphatic alcohols, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, n-amyl alcohol, isoamyl alcohol, tert-amyl alcohol, n-hexyl alcohol, cyclohexanol, n-octyl alcohol, 2-ethylhexanol, n-decyl alcohol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, ethylene glycol, propylene glycol, glycerol etc.; ethers, such as diethyl ether, di-n-propyl ether, diisopropyl ether, methyl n-butyl ether, ethyl n-butyl ether, di-n-butyl ether, di-n-amyl ether, diisoamyl ether, di-n-hexyl ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol dibutyl ether, 1,3-dioxolane, 1,4-dioxane, tetrahydrofuran; alcohol-ethers, such as diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, 2-butoxyethanol, tetrahydrofurfuryl alcohol, etc.; esters, such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, isobutyl acetate, methyl amyl acetate, 2-ethylhexyl acetate, diethyl succinate, etc.; nitriles, such as acetonitrile, propionitrile, butyronitrile, etc.; amides, such as formamide, acetamide, propionamide, N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, etc.; hydrocarbons, such as n-hexane, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane, 2,3-dimethylbutane, cyclohexane, n-heptane, 3-methylhexane, n-octane, 2,2,4-trimethylpentane, 2,3,4-trimethylpentane, n-decane, decalin, etc.
The hydrogenation may be run at temperatures ranging from room temperature or below, for example, 5°, to over 200°, for example 250°, preferably 25°-200° C., or other temperatures as high as the stability of the reactants and products will permit, and at pressures ranging from atmospheric pressure or below to pressures as high as economically practical, for example, up to 10,000 psi. Preferred is a somewhat elevated pressure of, for example, 10 psi, up to, for instance, 5000 psi, usually 100 to 2500 psi. Reaction times may vary widely, ranging from a few seconds to 24 hours or longer, usually 0.1 - 15 hours. The conditions may be varied to provide an optimum economic combination of temperature, pressure, catalyst level, and cycle time for any given starting material and catalyst.
The hydrogenation reaction may be carried out in either batch or continuous systems, with either tank or pipe-line or tubular reactors, operation in a manner well known to those skilled in the art.
The following examples will serve to illustrate the practice of the invention in more detail.
HYDROGENATION OF METHYL CARBANILATE EXAMPLE 1
A mixture of 15.1 g. (0.10 mole) of methyl carbanilate, 105 ml. of 2-propanol, and 0.60 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive (tradmark) autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was heated with agitation at 500-800 psig for 0.3 hr. at 25°-75°, followed by an additional 0.8 hr. at 75° with little or no gas absorption. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite (trademark) filter aid to remove the catalyst. The solvent was removed in a rotary evaporator under vacuum. The white solid residue was dried in a vacuum dessicator and consisted of 15.1 g. (96% yield) of methyl cyclohexylcarbamate, m.p. 73°-74°. An authentic sample prepared from cyclohexyl isocyanate and methanol melted at 73.5°-74°.
The examples in Table I illustrate the use of several catalysts for the nuclear hydrogenation of methyl carbanilate to methyl cyclohexylcarbamate. Rhodium is considerably more active than the other catalysts, and platinum shows no apparent activity.
                                  TABLE I                                 
__________________________________________________________________________
Hydrogenation of Methyl Carbanilate.sup.(a)                               
__________________________________________________________________________
Catalyst.sup.(b)             Yield methyl                                 
Example  wt.,                                                             
            conc.,                                                        
                Temp.,                                                    
                    Pressure,                                             
                         Time,                                            
                             cyclohexylcar-                               
No.  Metal                                                                
         g. g./l                                                          
                ° C                                                
                    psig.                                                 
                         hr. bamate, mole %                               
__________________________________________________________________________
1    Rh  0.60                                                             
             5  25-75                                                     
                    500-800                                               
                         0.3 96                                           
2    Ru  2.4                                                              
            20   75 500-800                                               
                         0.8 95                                           
3    Pd  2.4                                                              
            20  100 620-680                                               
                         2.8 22.sup.(c)                                   
4    Pd  2.4                                                              
            20  125 500-800                                               
                         13  47.sup.(c)                                   
5    Pt  2.4                                                              
            20  160 850  1.8  0.sup.(d)                                   
6    Ni  2.4                                                              
            20  150 660-880                                               
                         12.5                                             
                             30.sup.(c)                                   
7    Co  2.4                                                              
            20  150 500-900                                               
                         14.5                                             
                             45.sup.(c)                                   
__________________________________________________________________________
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel Magne Driv
 autoclave with 15.1 g. (0.10 mole) of methyl carbanilate and 105 ml. of  
 2-propanol.                                                              
 .sup.(b) The Rh, Ru, Pd and Pt catalysts were 5% metal on carbon. The Ni 
 and Co catalysts were 50% metal on kieselguhr; the weight of the catalyst
 is given as the weight of the metal plus support, in this and in         
 subsequent tables.                                                       
 .sup.(c) Determined by infrared analysis of residue product.             
 .sup.(d) No detectable reaction.
The effect of acid on the rate of hydrogenation of methyl carbanilate is shown in Table II. Traces of acid promote the rhodium, palladium, and platinum catalysts, but inhibit the ruthenium catalyst. The acid promotion is presumably due to the neutralization of traces of bases initially present and/or formed from the carbamate. The effect with rhodium is more pronounced at lower catalyst levels, when the catalyst is more susceptible to poisoning, and at higher temperatures, when larger amount of amine impurities would be expected (examples 10-12).
The effect of acid on platinum is dramatic and even permits reuse of the platinum catalyst (example 20).
The effect of acid on ruthenium seems to be the result of two opposing factors, an acid inhibition of the catalyst and the neutralization of basic inhibitors. The latter effect appears to increase in importance when lower catalyst levels produce longer reaction times that permit greater amine formation (examples 15 and 16).
                                  Table II                                
__________________________________________________________________________
Effect of Acid in Hydrogenation of Methyl Carbanilate.sup.(a)             
__________________________________________________________________________
Catalyst        Acid           Time for com-                              
Example  wt.,                                                             
            conc.,                                                        
                present                                                   
                     Temp.                                                
                         Pressure,                                        
                               plete conver-                              
No.  Metal                                                                
         g. g./l                                                          
                .sup.(b)                                                  
                     ° C.                                          
                         psig. sion, hr.                                  
__________________________________________________________________________
 8   Rh  0.20                                                             
            1.7 no   45  500-800                                          
                               4.0                                        
 9   Rh  0.20                                                             
            1.7 yes  45  500-800                                          
                               3.5                                        
10   Rh  0.10                                                             
            0.83                                                          
                no   100 500-800                                          
                               2.2                                        
11   Rh  0.10                                                             
            0.83                                                          
                yes  100 500-800                                          
                               0.9                                        
12   Rh  0.10                                                             
            0.83                                                          
                yes.sup.(c)                                               
                     100 500-800                                          
                               1.7                                        
13   Ru  2.4                                                              
            20  no   80  500-800                                          
                               0.7                                        
14   Ru  2.4                                                              
            20  yes  80  500-800                                          
                               2.7                                        
15   Ru  0.60                                                             
            5   no   90  500-800                                          
                               9.0                                        
16   Ru  0.60                                                             
            5   yes  90  500-800                                          
                               9.5                                        
 3   Pd  2.4                                                              
            20  no   100 620-680                                          
                               2.8 (22%                                   
                               conversion)                                
17   Pd  2.4                                                              
            20  yes  100 500-800                                          
                               2.2                                        
 5   Pt  2.4                                                              
            20  no   160 850   no conversion                              
18   Pt  2.4                                                              
            20  yes  45  500-800                                          
                               4.0                                        
19   Pt  0.8                                                              
            6.7 yes  75  500-800                                          
                               5.0                                        
20   Pt  d  d   yes  75  500-800                                          
                               8.8                                        
__________________________________________________________________________
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel, Magne    
 Drive autoclave with 15.1 g. (0.10 mole) of methyl carbanilate and 105 ml
 of 2-propanol.                                                           
 .sup.(b) 0.10 ml. (ca. 6 × 10.sup.-4 equiv.) of 6N sulfuric acid.  
 .sup.(c) 0.10 ml. (ca. 6 × 10.sup.-4 equiv.) of 6N acetic acid.    
 .sup.(d) Used catalyst recovered from example 19.
HYDROGENATION OF CYCLOHEXYL CARBANILATE EXAMPLE 21
A mixture of 21.9 g. (0.10 mole) of cyclohexyl carbanilate, 77 ml. of 2-propanol, and 3.0 g. of 5% on carbon was added to a 0.5-1., glass, low pressure, Parr (trademark) shaker bottle. The apparatus was assembled, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 50 psig. The reaction mixture was agitated at room temperature and 50 to 25 psig for 3.0 hr., followed by an additional 0.8 hr. with little or no gas absorption. The reaction product was filtered through Celite filter aid to remove the catalyst. The solvent was removed in a rotary evaporator under vacuum. The solid residue consisted of 22.3 g. (99% yield) of cyclohexyl cyclohexylcarbamate, m.p. 77°-78°. Anal. Calcd. for C13 H23 NO2 : C, 69.29; H, 10.30; N, 6.21. Found: C, 69.43; H, 10.10; N, 6.20.
EXAMPLE 22
A mixture of 21.9 g. (0.10 mole) of cyclohexyl carbanilate, 100 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 700 psig. The autoclave was agitated at 25° and 500-800 psig for 0.4 hr., followed by an additional 0.9 hr. with little or no gas absorption. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter aid to remove the catalyst. The solvent was removed in a rotary evaporator under vacuum. The white solid residue consisted of 21.9 g. (97% yield) of cyclohexyl cyclohexylcarbamate, m.p. 77°-78°.
HYDROGENATION OF METHYL 1-NAPHTHYLCARBAMATE EXAMPLE 23
A mixture of 20.1 g. (0.10 mole) of methyl 1-naphthylcarbamate, 100 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 22°-31° and 500-800 psig for 3.7 hr., followed by an additional 0.8 hr. with little or no gas absorption. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter aid to remove the catalyst. The solvent was removed in a rotary evaporator under vacuum. The solid residue consisted of 21.0 g. (99.5% yield) of a mixture of isomeric methyl 1-decahydronaphthylcarbamates, m.p. 104°-114°. Anal. Calcd. for C12 H21 NO2 : C, 68.20; H, 10.03; N, 6.63. Found: C, 68.61; H, 9.71; N, 6.69.
HYDROGENATION OF DIMETHYL 4,4'-METHYLENEDICARBANILATE
A. effect of purity of the dimethyl 4,4'-methylenedicarbanilate on the Rh-catalyzed hydrogenation
Table III illustrates how the purity of the N-aryl carbamate, in this case 4,4'-methylenedicarbanilate, greatly effects its rate of rhodium-catalyzed hydrogenation. Attempted hydrogenations of dimethyl 4,4'-methylenedicarbanilate that had been prepared under non-anhydrous conditions always resulted in catalyst poisoning and poor conversions.
              Table III                                                   
______________________________________                                    
Effect of Purity of Dimethyl 4,4'-Methylene-                              
dicarbanilate on Rate of Rh-Catalyzed Hydro-                              
genation to Dimethyl 4,4'-Methylenedicyclo-                               
hexylcarbamate.sup.(a)                                                    
______________________________________                                    
Source of    Catalyst           Time for com-                             
Example                                                                   
       Starting  wt.,   conc.,                                            
                              Temp.,                                      
                                    plete conver-                         
No.    Material.sup.(b)                                                   
                 g.     g./l. ° C.                                 
                                    sion, hr.                             
______________________________________                                    
24     I         2.4    20    50    6.5                                   
25      II       2.4    20    50    1.3                                   
26     I         0.8    6.7   100   5.3                                   
                                    (69% conversion)                      
27      II       0.8    6.7   100   0.7                                   
28      II       0.6    5     75    6.0                                   
29     III       0.6    5     75    3.0                                   
______________________________________                                    
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel, Magne    
 Drive autoclave with 20.0 g. (0.064 mole) of dimethyl                    
 4,4'-methylenedicarbanilate, 100 ml. of 2-propanol, and a 5% Rh on carbon
 catalyst at 500-800 psig.                                                
 .sup.(b) Each batch was prepared under anhydrous conditions from methanol
 and methylenebis(p-phenylisocyanate). I was prepared from practical grade
 methylenebis(p-phenylisocyanate). II was preapred from high purity       
 methylene-p-phenyl diisocyanate. III was prepared by recrystallization of
 II from methanol.
B. effect of temperature and catalyst level interaction on rate of Rh-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate
Table IV illustrates the interrelated effects of catalyst level and temperature on reaction rate and catalyst inhibition in the rhodium-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate. At the lower catalyst level (examples 30-32), catalyst poisoning produces a decrease in conversion in going from 75° to 100°, and, in spite of a very rapid initial rate of hydrogenation, even more severe poisoning and lower conversion at 150°. At the higher catalyst level (examples 33, 34 and 27), the catalyst poisoning is less pronounced because of the larger number of active sites, and the hydrogenation rate increases with increasing temperature in the lower range of 50° to 100°. The obvious explanation is that higher temperatures result in greater rates of nuclear hydrogenation, but also produce increasing quantities of by-products that poison the catalyst. The severity of poisoning will be inversely related to the amount of catalyst present.
              Table IV                                                    
______________________________________                                    
Relationship of Catalyst Level and Tem-                                   
perature in Rh-Catalyzed Hydrogenation of                                 
Dimethyl 4,4'-Methylenedicarbanilate.sup.(a)                              
______________________________________                                    
Catalyst                                                                  
Example                                                                   
       wt.,   conc.,  Temp.,                                              
                            Time for complete                             
No.    g.     g./l.   ° C.                                         
                            conversion, hr.                               
______________________________________                                    
30     0.4    3.3      75    13                                           
31     0.4    3.3     100   6.0 (65% conversion).sup.(b)                  
32     0.4    3.3     150   0.3 (50% conversion).sup.(c)                  
33     0.8    6.7      50    12                                           
34     0.8    6.7      75   3.0                                           
27     0.8    6.7     100   0.7                                           
______________________________________                                    
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel, Magne    
 Drive autoclave with 20.0 g. (0.064 mole) of dimethyl                    
 4,4'-methylenedicarbanilate, 100 ml. of 2-propanol, and a 5% Rh on carbon
 catalyst at 500-800 psig.                                                
 .sup.(b) Reaction going very slowly when shut down.                      
 .sup.(c) Reaction had stopped.
A detailed description of example 34 follows:
A mixture of 20.0 g. (0.064 mole) of dimethyl 4,4'-methylenedicarbanilate (batch II), 100 ml. of 2-propanol, and 0.8 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 75° and 500-800 psig for 3.0 hr., followed by an additional 0.8 hr. with little or no gas absorption. The gas absorption was aproximately quantitative. The autoclave was cooled and depressurized. The reaction product was removed and the catalyst separated from the reaction mixture by centrifugation, and then washed successively with three 600-ml. portions of methanol, one 300-ml. portion of 2-propanol, and one 150-ml. portion of 2-propanol. The solvent was removed from the reaction product in a rotary evaporator under vacuum. The white solid residue was dried in a vacuum dessicator and consisted of 20.4 g. (98% yield) of a mixture of isomers of dimethyl 4,4'-methylenedicyclohexylcarbamate, m.p. 128°-135°. Anal. Calcd. for C17 H30 N2 O4 : C, 62.56; H, 9.25; N, 8.58. Found: C, 63.10; H, 9.26; N, 8.35.
c. acid-activation of hydrogenation of dimethyl 4,4'-methylenedicarbanilate
The promotion by acid of the rhodium-, palladium-, and platinum-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate is shown in Table V. The results are similar to those obtained in the hydrogenation of methyl carbanilate (Table II). Again, rhodium is by far the most active catalyst.
                                  Table V                                 
__________________________________________________________________________
Acid Promotion in the Hydrogenation of                                    
Dimethyl 4,4'-Methylenedicarbanilate.sup.(a)                              
__________________________________________________________________________
Catalyst                          Time for                                
Example  wt.,                                                             
            conc.,                                                        
                Acid   Temp.,                                             
                           Pressure,                                      
                                  complete                                
No.  Metal                                                                
         g. g./l.                                                         
                present.sup.(b)                                           
                       ° C.                                        
                           psig   conversion, hr.                         
__________________________________________________________________________
34   Rh  0.8                                                              
            6.7 none   75  500-800                                        
                                  3.0                                     
35   Rh  0.8                                                              
            6.7 sulfuric                                                  
                       75  500-800                                        
                                  0.8                                     
36   Rh  0.8                                                              
            6.7 hydrochloric                                              
                       75  500-800                                        
                                  1.8                                     
37   Rh  0.8                                                              
            6.7 phosphoric                                                
                       75  500-800                                        
                                  1.4                                     
29   Rh  0.6                                                              
            5   none   75  500-800                                        
                                  3.0                                     
38   Rh  0.6                                                              
            5   sulfuric                                                  
                       75  500-800                                        
                                  1.0                                     
39   Rh  0.6                                                              
            5   sulfuric.sup.(c)                                          
                       75  500-800                                        
                                  0.8                                     
40   Pd  2.4                                                              
            20  none   100 1120-1155                                      
                                  5.0 (16% con-                           
                                  version)                                
41   Pd  2.4                                                              
            20  sulfuric                                                  
                       100  900-1200                                      
                                  5.0 (34% con-                           
                                  version)                                
42   Pt  2.4                                                              
            20  none   125 725    no conversion                           
43   Pt  2.4                                                              
            20  sulfuric                                                  
                       85  500-800                                        
                                  5.6 (82% con-                           
                                  version)                                
__________________________________________________________________________
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel,          
 Magne-Drive autoclave with 20.0 g. (0.064 mole) of dimethyl              
 4,4'-methylenedicarbanilate, 100 ml. of 2-propanol, and a 5% metal on    
 carbon catalyst.                                                         
 .sup.(b) 0.10 ml. (ca. 6 × 10.sup.-4 equiv.) of acid used.         
 .sup.(c) 0.50 ml. (ca. 30 × 10.sup.-4 equiv.).
D. catalyst reuse in Rh-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate
Table VI illustrates how the rhodium catalyst recovered from the hydrogenation of dimethyl 4,4'-methylenedicarbanilate retains sufficient activity to permit several reuses. Furthermore, examples 48 and 49 illustrate how extremely efficient an acid wash is in restoring the activity of the used catalyst. Part of the enhanced activity in these experiments may be the result of acid promotion (see Tables II and V) by traces of acid remaining on the catalyst from the acid wash.
              Table VI                                                    
______________________________________                                    
Catalyst Reuse in Rh-Catalyzed Hydrogena-                                 
tion of Dimethyl 4,4'-Methylenedicarbanilate.sup.(a)                      
______________________________________                                    
                                  Time for com-                           
Example                  Catalyst plete conver-                           
No.       Catalyst       treatment                                        
                                  sion, hr.                               
______________________________________                                    
34     0.8 g. (6.7 g./l.) fresh                                           
                         none     3.0                                     
44     recovered from example 34                                          
                         b        4.0                                     
45     recovered from example 44                                          
                         b        5.0                                     
46     recovered from example 45                                          
                         b        8.4                                     
28     0.6 g. (5.0 g./l.) fresh                                           
                         none     6.0                                     
47     recovered from example 28                                          
                         b        9.0                                     
48     recovered from example 47                                          
                         c        4.3                                     
49     recovered from example 48                                          
                         c        6.0                                     
______________________________________                                    
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel, Magne    
 Drive autoclave with 20.0 g. (0.064 mole) of dimethyl                    
 4,4'-methylenedicarbanilate, 100 ml. of 2-propanol and a 5% Rh on carbon 
 catalyst at 75° and 500-800 psig.                                 
 .sup.(b) Washed successively with methanol and 2-propanol.               
 .sup.(c) Washed successively with methanol, 6N sulfuric acid, and        
 2-propanol.
Table VII shows the feasibility of catalyst reuse in the rhodium-catalyzed hydrogenation of dimethyl 4,4'-methylenedicarbanilate with acid promotion, both with and without an acid wash of the recovered catalyst.
              Table VII                                                   
______________________________________                                    
Catalyst Reuse in Acid-Promoted Rh-Catalyzed                              
Hydrogenation of Dimethyl 4,4'-Methylenedi-                               
carbanilate.sup.(a)                                                       
______________________________________                                    
                                      Time for                            
                                      complete                            
Example              Catalyst Promoting                                   
                                      conver-                             
No.      Catalyst    treatment                                            
                              Acid    sion, hr.                           
______________________________________                                    
35     0.8 g. (6.7 g./l.)                                                 
       fresh         None     Sulfuric                                    
                                      0.8                                 
50     recovered from                                                     
       example 35    b        Sulfuric                                    
                                      1.8                                 
37     0.8 g. (6.7 g./l.)                                                 
       fresh         None     Phosphoric                                  
                                      1.4                                 
51     recovered from                                                     
       example 37    c        Phosphoric                                  
                                      1.8                                 
______________________________________                                    
 .sup.(a) Each experiment was run in a 300-ml., stainless-steel, Magne    
 Drive autoclave with 20.0 g. (0.064 mole) of dimethyl                    
 4,4'-methylenedicarbanilate, 100 ml. of 2-propanol, a 5% Rh on carbon    
 catalyst, and 0.10 ml. (ca. 6 × 10.sup.-4 equiv.) of either 6N     
 sulfuric acid or 6N phosphoric acid at 75° and 500-800 psig.      
 .sup.(b) Washed successively with methanol and 2-propanol.               
 .sup.(c) Washed successively with methanol, 6N sulfuric acid, and        
 2-propanol.
HYDROGENATION OF DIISOPROPYL 4,4'-METHYLENEDICARBANILATE EXAMPLE 52
A mixture of 23.6 g. (0.064 mole) of diisopropyl 4,4'-methylenedicarbanilate, 97 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 40° and 500-800 psig for 7.6 hr., followed by an additional 1.1 hr. with little or no gas absorption. The autoclave was cooled and depressurized. The reaction product was removed and filtered through Celite filter aid to remove the catalyst. The solvent was removed on a rotary evaporator under vacuum. The solid residue consisted of 20.2 g. (83% yield) of a mixture of isomeric diisopropyl 4,4'-methylenedicyclohexylcarbamates, m.p. 182°-206°, Anal. Calcd. C21 H38 N2 O4 : C, 65.93; H, 10.01; N, 7.32. Found: C, 66.39; H, 10.24; N, 7.48.
EXAMPLE 53
Example 52 was repeated at 75° for 6.0 hr. Approximately the theoretical gas absorption took place in 3.0 hr., with most of the reaction completed below reaction temperature, followed by a slow gas absorption for 3.0 hr. at 75° and little or no absorption in the last 3.0 hr. at 75°.
HYDROGENATION OF DIMETHYL TOLUENEDICARBAMATE EXAMPLE 54
A mixture of 23.8 g. (0.10 mole) of dimethyl toluenedicarbamates (prepared from the 80:20 mixture of 2,4- and 2,6-toluene diisocyanates), 100 ml. of 2-propanol and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at room temperature and 500-800 psig for 2.8 hr., with little or no gas absorption in an additional 0.8 hr. The autoclave was depressurized and the reaction product removed and filtered through Celite filter aid to remove the catalyst. The solvent was removed on a rotary evaporator under vacuum. The solid white residue consisted of 24.9 g. (102% yield) of a mixture of isomeric dimethyl methylcyclohexyldicarbamates, m.p. 165°-189°. Anal. Calcd. for C11 H20 N2 O4 : C, 54.07; H, 8.27; N, 11.46. Found: C, 54.24; H, 8.23; N, 11.44.
HYDROGENATION OF DIMETHYL 1,5-NAPHTHALENEDICARBAMATE EXAMPLE 55
A mixture of 15.1 g. (0.055 mole) of dimethyl 1,5-naphthalenedicarbamate, 105 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300-ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 45° and 500-800 psig for 3.8 hr., with little or no gas absorption in an additional 1.3 hr. The reaction product was removed and filtered through Celite filter aid to remove the catalyst. The solvent was removed on a rotary evaporator under vacuum. The solid white residue consisted of 14.2 g. (91% yield) of a mixture of isomeric dimethyl 1,5-decahydronaphthalenedicarbamates, m.p. 211°-233°. Anal. Calcd. for C14 H24 N2 O4 : C, 59.14; H, 8.51; N, 9.85. Found: C, 59.20; H, 8.57; N, 9.79.
HYDROGENATION OF ETHYL N-METHYLCARBANILATE EXAMPLE 56
A mixture of 17.9 g. (0.10 mole) of ethyl N-methylcarbanilate, 100 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300 ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 30°-40° and 500-800 psig for 0.3 hr., when gas absorption stopped. The reaction product was removed and filtered through Celite filter aid to remove the catalyst. Most of the solvent was removed on a rotary evaporator under vacuum. Distillation gave a quantitative yield of ethyl N-methylcyclohexylcarbamate, b.p. 78°-82° at 2 mm., mostly 81°-2° at 2 mm. An elemental analysis was obtained on a middle cut from the distillation. Anal. Calcd. for C10 H19 O2 N: C, 64.83; H, 10.34; N, 7.56. Found: C, 64.73; H, 10.32; N, 7.44.
HYDROGENATION OF DIETHYL 4,4'-METHYLENEDI(N-METHYLCARBANILATE) EXAMPLE 57
A mixture of 29.5 g. (0.0796 mole) of diethyl 4,4'-methylenedi(N-methylcarbanilate), prepared by the reaction of 4,4'-methylenebis (N-methylaniline) with ethyl chloroformate in benzene in the presence of calcium carbonate, 90 ml. of 2-propanol, and 2.4 g. of 5% Rh on carbon was added to a 300 ml. Magne Drive autoclave. The vessel was sealed, purged first with nitrogen and then with hydrogen, and pressured with hydrogen to 600 psig. The autoclave was agitated at 425-800 psig. for 7 hr. at 50° followed by 13 hr. at 75°, with little or no gas absorption in the last 2 hr. The hydrogen absorption was approximately quantitative. The reaction product was removed and filtered through Celite filter aid to remove the catalyst. The solvent was removed on a rotary evaporator. After drying in a vacuum dessicator over Drierite, the viscous liquid residue consisted of 29.5 g. (97% yield) of a mixture of isomers of diethyl 4,4'-methylenedi(N-methylcyclohexylcarbamate). Anal. Calcd. for C21 H38 N2 O4 : C, 65.94; H, 10.01; N, 7.32. Found: C, 66.26; H, 10.06; N, 7.41.

Claims (18)

We claim:
1. A method of making an N-alicyclic carbamate comprising contacting an N-aryl carbamate with hydrogen in an inert solvent medium in the presence of a metal hydrogenation catalyst selected from the group consisting of rhodium, acid-treated rhodium, ruthenium, palladium, acid-treated palladium, nickel, cobalt and acid-treated platinum catalyst, whereby nuclear hydrogenation of the said N-aryl carbamate takes place to form the said N-alicyclic carbamate, the said N-aryl carbamate being selected from the group consisting of those of the formulas I and II as follows: ##STR2## wherein, in formula I: n is an integer having a value from 1 to 3; R is alkyl having from 1 to 18 carbon atoms, a cycloalkyl group having from 5 to 8 carbon atoms, an aryl group having from 6 to 12 carbon atoms, an aralkyl or alkaryl group having from 7 to 12 carbon atoms; R1 is hydrogen, an alkyl group having from 1 to 8 carbon atoms, a cycloalkyl group having from 5 to 8 carbon atoms, or an aryl group having from 6 to 12 carbon atoms; and Ar is an aryl group having a valence of n and having from 6 to 18 carbon atoms, containing up to 4 fused rings;
and wherein, in formula II: a and b are integers having values of 1 or 2; R2 and R6 are the same or different and have meanings stated for R in formula I; R3 and R5 are the same or different and have meanings stated for R1 in formula I; R4 is a single bond, --O--, C1 -C8 alkylene, C5 -C8 cycloalkylene, C2 -C8 alkylidene, or C2 -C8 alkenylene; and Ar1 and Ar2 are the same or different and are divalent or trivalent groups derived from radicals having the meanings assigned to Ar in formula I;
the said method being carried out at a temperature of 25°-200° C and a pressure of 100 to 2500 psi.
2. A method as in claim 1 in which the said hydrogenation catalyst is rhodium or ruthenium catalyst.
3. A method as in claim 1 in which the said hydrogenation catalyst is rhodium catalyst.
4. A method as in claim 1 in which the said hydrogenation catalyst is acid-treated rhodium, acid-treated palladium, or acid-treated platinum catalyst.
5. A method as in claim 1 in which the said hydrogenation catalyst is acid-treated rhodium catalyst.
6. A method as in claim 5 in which the starting N-aryl carbamate is methyl carbanilate and the resulting N-alicyclic carbamate product is methyl cyclohexylcarbamate.
7. A method as in claim 5 in which the starting N-aryl carbamate is cyclohexyl carbanilate and the resulting N-alicyclic carbamate product is cyclohexyl cyclohexylcarbamate.
8. A method as in claim 1 in which the starting N-aryl carbamate is methyl 1-naphthylcarbamate and the resulting N-alicyclic carbamate product is a mixture of isomeric methyl 1-decahydronaphthylcarbamates.
9. A method as in claim 5 in which the starting N-aryl carbamate is ethyl N-methylcarbanilate and the resulting N-alicyclic carbamate product is ethyl N-methylcyclohexylcarbamate.
10. A method as in claim 5 in which the starting N-aryl carbamate is diethyl 4,4'-methylenedi(N-methylcarbanilate) and the resulting N-alicyclic carbamate product is a mixture of isomers of diethyl 4,4'-methylenedi(N-methylcyclohexylcarbamate).
11. A method as in claim 1 in which n is 2, R is an alkyl group having from 1 to 4 carbon atoms, a cycloalkyl group having 5 to 6 carbon atoms, phenyl, tolyl, xylyl, ethylphenyl, benzyl, or phenethyl, R1 is hydrogen, Ar is phenylene, tolylene or naphthylene, R2 and R6 have meanings stated herein for R; R3 and R5 have meanings stated herein for R1 ; and Ar1 and Ar2 are phenylene, tolylene, xylylene or biphenylene.
12. A method as in claim 11 in which the inert organic solvent is an aliphatic alcohol.
13. A method as in claim 11 in which the hydrogenation catalyst is rhodium catalyst, with or without acid treatment.
14. A method as in claim 13 in which the catalyst is acid-treated.
15. A method as in claim 13 in which the starting N-aryl carbamate is dimethyl 4,4'-methylenedicarbanilate and the resulting N-alicyclic carbamate product is a mixture of isomers of dimethyl 4,4'-methylenedicyclohexylcarbamate.
16. A method as in claim 13 in which the starting N-aryl carbamate is diisopropyl 4,4'-methylenedicarbanilate and the resulting N-alicyclic carbamate product is a mixture of isomers of diisopropyl 4,4'-methylenedicyclohexylcarbamate.
17. A method as in claim 13 in which the starting N-aryl carbamate is dimethyl toluenedicarbamate and the resulting N-alicyclic carbamate is a mixture of isomers of dimethyl methylcyclohexyldicarbamate.
18. A method as in claim 13 in which the starting N-aryl carbamate is dimethyl 1,5-naphthalenedicarbamate and the resulting N-alicyclic carbamate product is a mixture of isomers of dimethyl 1,5-decahydronaphthalenedicarbamate.
US05/610,359 1975-09-04 1975-09-04 Nuclear hydrogenation of n-aryl carbamates Expired - Lifetime US4069240A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
US05/610,359 US4069240A (en) 1975-09-04 1975-09-04 Nuclear hydrogenation of n-aryl carbamates
CA259,244A CA1075259A (en) 1975-09-04 1976-08-17 Nuclear hydrogenation of n-aryl carbamates
IT69159/76A IT1070301B (en) 1975-09-04 1976-09-03 PREVIOUS FOR THE PERARATION OF CARBAMATES N AL ICICLICI
GB36565/76A GB1551832A (en) 1975-09-04 1976-09-03 Nuclear hydrogenation of n-aryl carbamates
DE19762639842 DE2639842A1 (en) 1975-09-04 1976-09-03 NUCLEAR HYDROGENATION OF N-ARYLCARBAMATES
FR7626711A FR2322859A1 (en) 1975-09-04 1976-09-03 PROCESS FOR NUCLEAR HYDROGENATION OF N-ARYL CARBAMATES AND N-ALICYCLIC CARBAMATES OBTAINED BY THE PROCESS
JP51105077A JPS5233653A (en) 1975-09-04 1976-09-03 Process for manufacture of nnalicyclic crbamate

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US05/610,359 US4069240A (en) 1975-09-04 1975-09-04 Nuclear hydrogenation of n-aryl carbamates

Publications (1)

Publication Number Publication Date
US4069240A true US4069240A (en) 1978-01-17

Family

ID=24444700

Family Applications (1)

Application Number Title Priority Date Filing Date
US05/610,359 Expired - Lifetime US4069240A (en) 1975-09-04 1975-09-04 Nuclear hydrogenation of n-aryl carbamates

Country Status (7)

Country Link
US (1) US4069240A (en)
JP (1) JPS5233653A (en)
CA (1) CA1075259A (en)
DE (1) DE2639842A1 (en)
FR (1) FR2322859A1 (en)
GB (1) GB1551832A (en)
IT (1) IT1070301B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR970010809A (en) * 1995-08-10 1997-03-27 클라우스 로이터, 귄터 슈마허 METHOD FOR PREPARING LOW-EMITTING POLYURETHANE MOLDINGS AND COMPOSITIONS
US20040097661A1 (en) * 2002-11-18 2004-05-20 Degussa Ag Method for hydrogenation of aromatic urethanes in the presence of a supported rutheniun catalyst
CN114644576A (en) * 2022-04-21 2022-06-21 中国科学院过程工程研究所 1, 3-cyclohexanedimethylene dicarbamate and preparation method and application thereof
WO2023168889A1 (en) * 2022-03-07 2023-09-14 中国科学院过程工程研究所 Preparation method for alicyclic carbamate and use thereof

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5182296A (en) * 1989-10-26 1993-01-26 Tanabe Seiyaky Co., Ltd. Naphthyloxazolidone derivatives
DE10253803A1 (en) * 2002-11-18 2004-05-27 Degussa Ag Process for the preparation of aliphatic isocyanates from aromatic isocyanates

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3511875A (en) * 1968-04-12 1970-05-12 Du Pont Herbicidal alkylcarbamoyloxy semicarbazides
US3567764A (en) * 1968-04-12 1971-03-02 Du Pont Herbicidal alkylcarbamoyloxyphenyl biurets
US3600426A (en) * 1968-09-30 1971-08-17 American Home Prod 1-aminocyclopentanecarboxylic acid esters
US3691234A (en) * 1969-06-20 1972-09-12 Basf Ag N-acylated cycloalkylhydroxylamines
US3699149A (en) * 1968-10-14 1972-10-17 Daiichi Seiyaku Co Phenyl esters of t-amcha
US3867443A (en) * 1972-02-22 1975-02-18 Uniroyal Inc Nuclear hydrogenation of n-aryl polyamides

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3511875A (en) * 1968-04-12 1970-05-12 Du Pont Herbicidal alkylcarbamoyloxy semicarbazides
US3567764A (en) * 1968-04-12 1971-03-02 Du Pont Herbicidal alkylcarbamoyloxyphenyl biurets
US3600426A (en) * 1968-09-30 1971-08-17 American Home Prod 1-aminocyclopentanecarboxylic acid esters
US3699149A (en) * 1968-10-14 1972-10-17 Daiichi Seiyaku Co Phenyl esters of t-amcha
US3691234A (en) * 1969-06-20 1972-09-12 Basf Ag N-acylated cycloalkylhydroxylamines
US3867443A (en) * 1972-02-22 1975-02-18 Uniroyal Inc Nuclear hydrogenation of n-aryl polyamides

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
Scopes et al., J. Chem. Soc., 1972, 2810-2811. *
Weaver et al., Chem. and Ind., 4, pp. 187-188 (1973). *
Weaver et al., Preprints, General Papers, Div. of Petrol. Chem., 18 (1), pp. 196-199 (1973). *

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR970010809A (en) * 1995-08-10 1997-03-27 클라우스 로이터, 귄터 슈마허 METHOD FOR PREPARING LOW-EMITTING POLYURETHANE MOLDINGS AND COMPOSITIONS
US20040097661A1 (en) * 2002-11-18 2004-05-20 Degussa Ag Method for hydrogenation of aromatic urethanes in the presence of a supported rutheniun catalyst
US6809215B2 (en) * 2002-11-18 2004-10-26 Degussa Ag Method for hydrogenation of aromatic urethanes in the presence of a supported ruthenium catalyst
CN1296350C (en) * 2002-11-18 2007-01-24 德古萨公司 Method for hydrogenation of aromatic urethanes in the presence of a supported rutheniun catalyst
WO2023168889A1 (en) * 2022-03-07 2023-09-14 中国科学院过程工程研究所 Preparation method for alicyclic carbamate and use thereof
CN116768763A (en) * 2022-03-07 2023-09-19 中国科学院过程工程研究所 Preparation method and application of alicyclic carbamate
CN114644576A (en) * 2022-04-21 2022-06-21 中国科学院过程工程研究所 1, 3-cyclohexanedimethylene dicarbamate and preparation method and application thereof

Also Published As

Publication number Publication date
FR2322859A1 (en) 1977-04-01
FR2322859B1 (en) 1982-02-19
JPS5233653A (en) 1977-03-14
CA1075259A (en) 1980-04-08
GB1551832A (en) 1979-09-05
IT1070301B (en) 1985-03-29
DE2639842A1 (en) 1977-03-17

Similar Documents

Publication Publication Date Title
US3336386A (en) Hydrogenation with platinum metal sulfide catalyst
US3895054A (en) Process for the manufacture of urethanes
KR850004457A (en) Process for preparing butane-1,4-diol
US4482741A (en) Preparation of xylylenediamine
US4069240A (en) Nuclear hydrogenation of n-aryl carbamates
US3479392A (en) Production of unsaturated ethers and esters
US3538161A (en) Reductive alkylation of aromatic amino compounds utilizing platinum metal selendies and tellurides as catalysts
CA2015251A1 (en) Amination of carbonyls
US3956360A (en) Process for the manufacture of urethanes
US4248799A (en) Hydrogenation of nitriles in ammonia and water
GB797483A (en) Improvements in or relating to catalytic hydrogenation of nitrosamines
US4310714A (en) Hydrogenation of α-pinene to cis-pinane
EP0067058A1 (en) Production of cyclohexylamine
US3935264A (en) Hydrogenation of dinitrotoluene to toluene diamine
US2606926A (en) Process for preparing cyclohexane-diamines predominantly in the cis form
US3054819A (en) Preparation of organic isocyanates
US4331557A (en) Regeneration of ruthenium-containing catalyst
US4717774A (en) Process for the preparation of toluene diamines
US3989761A (en) Production of orthophenylphenols
US2908722A (en) Process for preparing saturated monohydric alcohols
US3928451A (en) Method of preparing p-chlorophenylenediamine
US3867443A (en) Nuclear hydrogenation of n-aryl polyamides
US3093685A (en) Catalytic reduction of aromatic mononitro compounds
US3213141A (en) Catalytic reduction of aromatic dinitro compounds
US3278611A (en) Hydrogenation of aromatic halides

Legal Events

Date Code Title Description
AS Assignment

Owner name: UNIROYAL CHEMICAL COMPANY, INC., WORLD HEADQUARTER

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:UNIROYAL, INC., A NEW YORK CORP.;REEL/FRAME:004488/0204

Effective date: 19851027

AS Assignment

Owner name: UNIROYAL CHEMICAL COMPANY, INC., WORLD HEADQUARTER

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE DATE OCTOBER 27, 1985.;ASSIGNOR:UNIROYAL, INC., A NJ CORP.;REEL/FRAME:004754/0186

Effective date: 19870130